Optical fibers have been used for many years in the medical field for surgical applications using high power lasers. The optical fibers are used primarily in their basic form, consisting of a core, cladding, primary coating (buffer) and a jacket. As such they do not contain much in the way of strengthening or protective layers which are typically added to the optical fiber when used as cables in telecom applications for example. The core and cladding are typically made with silica glass with cores ranging in diameter from 200 um (small core) to 1000 um (large core), thus the optical fibers, consisting of thin strands of glass, are easily damaged or broken with handling and shipping. The optical fibers are also typically attached at one end (proximal end) to a large and relatively heavy (compared to small core optical fibers) metal ferrule assembly (connector) which is used to facilitate connection of the optical fiber to the laser system. The complete assembly, the optical fiber and the connector are known generally as a surgical fiber. Thus there is a strong need for suitable packaging in order to protect the surgical fiber until it is used for the clinical procedure, helping to ensure safety and efficacy.
Packaging of surgical fibers presents many unique requirements including but not limited to the following. Small core optical fibers are extremely fragile whereas large core optical fibers are extremely stiff and can become quite dangerous when wound tightly under tension. The glass of the optical fiber is typically exposed by removing the jacket or jacket and buffer for a number of millimeters at the application end (distal end) and the glass core/cladding is cleaved, presenting a sharp edge around the perimeter which is easily chipped or damaged. Optical fibers are typically provided in short lengths on the order of 3 meters. The metal ferrule assembly, if not secured, could easily break the optical fiber during typical shipping conditions. The surgical fibers are generally supplied sterile therefore packaging must be able to withstand sterilization cycles, such as Ethylene Oxide or Steam sterilization, which can present extremes in temperature and pressure. As well the packaging must be able to maintain sterility and product functionality over extremes in temperature, humidity, vibration and shock which are typically encountered when shipped throughout the world. Surgical fibers can be sold as single use devices and the device and packaging discarded, thus packaging cost is a consideration. Surgical fibers must be easily dispensed into the sterile field within the operating room.
Numerous designs are currently available, the most common being a single plane card, either plastic or cardboard which is die cut and has numerous tabs, raised at angles from the card, which allow the optical fibers and connectors to be held onto the card. The optical fibers are typically wound around a number of these tabs and opposing tabs hold the connector. These designs exhibit a number of limitations such as the creation of pinch points, which can damage the jacket of the optical fiber or fracture the glass, and difficulty in removing the optical fibers by the end user as the optical fiber must be removed one tab at a time or in its entirety removing the wound optical fiber as one unit. Once the removal process has started, it is difficult to stop as the optical fiber will start to disengage from the tabs by itself. A multitude of tabs is required in order to support optical fibers of different sizes on a single card design as the large optical fibers are very rigid and small optical fibers are very flexible. Holding large core optical fibers is more difficult as under tight diameters, the optical fiber exhibits a lot of force on the tabs, with a tendency for the optical fiber to spring off the card. Also, it is difficult to control the exact resting location of the cleaved distal end of the optical fiber on the card as surgical fibers can vary slightly in length during production resulting in the cleaved distal end falling in unsuitable locations, in the round of a corner for example, with the end of the optical fiber unsecure or just under a tab for example, where the end of the optical fiber can easily pop out during transit. This exposed cleaved glass end is thus easily damaged on these tabs or presents a risk to the primary sterile barrier, typically a tyvek/plastic film pouch, which could be punctured by the sharp edge of the cleaved distal tip, should it spring loose of a tab.
Most current designs are not capable of supporting adequately multiple sizes (diameters) of surgical fibers due to the significant variance in mechanical properties. Large core optical fibers are very rigid while small core optical fibers are flexible. Bending large core optical fibers into a small radius (<0.5 meters) requires a large amount of force. Small core optical fibers can bend into a very small radius (a few cm) and require very little force. Both optical fibers, if not held securely will tend to come loose easily during transport. Large core optical fiber holders require a great deal of rigidity in order to counteract the forces exerted by the optical fiber when bent. Small core optical fibers require the optical fiber to be wound tightly on the holder, requiring the holder to be pliable in order to avoid pressure points on the optical fiber. These two requirements conflict with each other, thus current designs do not provide suitable packaging for the optical fibers.